At Iggesund’s laboratory, paperboard is cut into strips before being sampled by advanced machines and human noses.
Smell that box
Paperboard has a long history in food packaging. But unless it’s made right, it could taint the flavour or odour of the product. This is the raison d’être for Iggesund’s Laboratory for Sensory and Chemical Analyses, one of the world’s leading facilities for addressing this issue with paperboard-based packaging.
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“Pinch your nose. And taste this powder. Which flavour is it? Keep your nose pinched.” Dr Gunnar Forsgren, technical manager of the Laboratory for Sensory and Chemical Analyses, is conducting a test for some visitors at the lab in Strömsbruk, Sweden, four hours north of Stockholm.
The photographer, the assistant and I look at each other and say in unison: “Sugar.”
“OK, let go of your nose.
”We can hardly believe the cinnamon explosions on our palates.
“Now you understand sensory and chemical interactivity between various substances,” Forsgren says. “They are not just the sum of one another – often something completely new occurs. I like to think of it as an orchestra.”
Forsgren and chemist Torgny Ljungberg, leisurely dressed in checked shirts, slacks and rubber-soled shoes, guide us through the unassuming red-brick building surrounded by vast forests. Rooms are stacked top to bottom with glass flasks, paper samples wrapped in isolating tinfoil, test tubes, ovens and gas chromatographs hooked up to analysing computers. Most of the work is about making sure that packaging for food and tobacco does not taint the product in a deterioriating way.
Performing these tests is extremely complex, but the basic principle is simple. Cut-up strips of paperboard are placed in enclosed glass tubes. After a day, the air in the tube is pressed with the aid of helium through an absorbent, often a polymer material with a high surface area. This absorbent is heated to release the substances, and then the gas chromatograph goes to work separating the mixture. However, machines have a key limitation. “They tell you the quantity of certain volatile substances, but not the experience of the smell,” Forsgren says. “An experienced smell is always subjective.”
The testing panel, consisting of 25 consultants from surrounding villages, is one of the most important components in the laboratory. The work of the panel means mostly sniffing glass flasks containing cut-up paperboard strips, or tasting chocolate that has been stored with paperboard strips to be used in food packaging. The samples are presented anonymously in random order. If all goes well, the panel will not use such suggested flavours as moist, rank, bitter, rubber, cardboard or printing ink when they fill out their test sheets.
“Our work is about finding deviations that shouldn’t be there,” Forsgren explains.
At the Laboratory for Sensory and Chemical Analyses the human nose is combined with the latest technology.
So how much of a substance is required in order for you to sense odorants flowing up your nose? The machines measure nanograms per liter (one-billionths of a gram, or 0.000000001 gram/l), but the 300 genetically different receptors in the human nose can register some substances that occur in 10,000ths of a nanogram. No wonder that if a conflict arises, the human noses of the panel have veto power over the machines.
“Unfortunately, companies are not very aware that packaging can spoil a food product,” Forsgren says. “They should really consider the choice of printing ink, the amount of ink, factors like direct and indirect contact with the product, time and storage – for instance, light might trigger decay. Paperboard is neutral, but it is a living, organic material. All organic matter interacts more or less, and our goal is to make sure that the interaction is as small as possible.”
Ljungberg adds, “The worst example I have seen had 400 percent colour on the inside of a chocolate box. Of course, that is a potential source of problems. But we also know that you could have a good paperboard product and a good printing ink, and still the combination can be a disaster.”
Before we leave the lab, Forsgren points out that the Laboratory for Sensory and Chemical Analyses has been certified by Swedish authorities since 2002. “We are the only packaging-related certified sensory lab in Sweden, and one of around 30 in the world,” he says. “Thus we are objective like an authority, but we have the flexibility to perform tests for our clients within days, should the need arise.”
You may have heard of active packaging. One such product has oxygen-consuming enzymes in the finishing treatment, which slow down the decaying process of the packaged food product. There is also packaging with iron flakes, where the iron attracts oxygen that might enter the package, thus prolonging the life of the food product. A third example is labels that change colour if the temperature is too high. Then you will know if and where the cool chain has been broken along the way.
What does the law* say?
Packaging must not transfer its constituents to food in quantities that could:
• endanger human health;
• bring about an unacceptable change in the composition of the food; or
• bring about a deterioration in the food’s
organoleptic (taste and smell) characteristics.
Iggesund interprets this rather vague law by guaranteeing that its paperboard will not give
a higher flavour to chocolate than “just notice-able”, or a ranking of 1 on a scale of 4. The guarantee is valid for one year, as long as the paperboard has been stored correctly.
* Regulation (EC) No 1935/2004 of the European Parliament and of the Council of 27 October 2004 on materials and articles intended to come into contact with food and repealing Directives 80/590/EEC and 89/109/EEC.
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